Struggling to put on weight to get pregnant 😪

I'm 4'9 and 82 pounds. If I want to get pregnant I was told to put on just a little weight I've been eating meals 3 times a day and I will only gain like a pound then the next day I would lose it like what the hell my metabolism is just very fast this is my 10th month of trying but I wish I was thick or the right weight I wouldn't have no problem getting pregnant at all why just why the fuck does my body have to be like this it's been like that my whole life and I'm not even anorexic or have a eating disorder I plan to work with a nutritionist but I want to get pregnant soonÂ